1. Field of the Invention
This invention relates to the field of insulated roof structures and more particularly to the field of supporting roof liner panels and insulation material in commercial structures.
2. Description of the Prior Art
In the construction of a roof for a building, usually a plurality of longitudinally extending beams are regularly spaced at predetermined distances from each other, for example, 18, 20, or 24 feet, to form a plurality of longitudinally extending bays. These beams support a plurality of laterally extending purlins, also regularly spaced at predetermined distances, such as five feet, from each other. The purlins are usually of a cross section, such as a "C" or "Z" shape, providing a lower flange. The lower flange of each purlin is firmly secured to the beams by appropriate rivets or screws.
After the purlins are secured to the beams, roof liner panels of a predetermined width corresponding to the distance between the purlins, such as five feet, are attached to the lower flanges of adjacent pairs of purlins by means of screws or rivets.
Batts of insulation material are then rolled out between the purlins on top of the roof liner panels, and roof panels are then securely fastened to the top flanges of the purlins.
The process of attaching the roof liner panels to the lower flanges of the purlins by means of rivets or screws is a very time consuming one, involving difficult working conditions, and resultant higher labor costs. Furthermore, the use of metal roof panels, steel purlins, and steel rivets or screws in such conventional roof structures creates a continuous path of thermal conductivity running from the roof, through purlins and fasteners, to the inside of the building. In cold weather the interaction of this thermal path with the heated inside air can result in condensation of moisture on the liner panel fasteners, and the dripping of water from the ceiling inside the building.